You shouldn't really say that i'm better than you since that is looking down on people, and only Allaah knows who is better. So we leave that upto Allaah. Looking down on people can also be a form of arrogance.
'Abdullah ibn Mas'ud reported that the Prophet, may Allah bless him and grant him peace, said, "No one who has an atom's weight of pride in his heart will enter the Garden."
A man said, "And if the man likes his clothes to be good and his sandals to be good?" He said, "Allah is Beautiful and loves beauty. Pride means to renounce the truth and abase (look down on) people." [Sahih Muslim]
The best thing to do is to stop/forbid the evil act anyway, even if you do sins. Since all of the children of Adam sin, but the best of sinners are those that repent.
If they insult you by saying you do worser sins, then that is also a reality check for the person who is enjoining the good/forbidding the evil to do the permissible instead of doing the forbidden.
And Allaah knows best.